I would say a scope that has .5" error in it is probably rare, that's a lot. Something would have to fall apart inside and or the reticle breaks loose. The consistency in a rifle doesn't come easy. Factory guns can shoot fairly well, most times, but not all the time. I'm no AR guy, but I assume they would be no different. Find yourself a guy shooting a bench gun, give him a few bucks, and ask him to put your scope on his gun, and try it.
